Gimbal optical system for document image capture

ABSTRACT

An imaging device for document imaging may comprise a housing and an optical system having a lens system and an optical detector. The optical system is responsive to image light reflected by an object and produces image data representative of the image light. The optical system is pivotally mounted to said housing and is biased toward a vertical orientation inside said housing by gravity.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation of application Ser. No. 09/311,527 filed on May13, 1999, which is hereby incorporated by reference herein.

FIELD OF THE INVENTION

The present invention relates generally to the field of documentimaging, and more particularly, to a system and method for verticallyorienting an optical path in a digital camera.

BACKGROUND OF THE INVENTION

Imaging devices such as optical cameras and scanners are well known inthe art and may be used to quickly and easily capture the image of adocument for numerous applications. The images may be processed andstored either chemically on photographic paper, or electronically in theform of electrical signals, either analog or digital. As computer usebecomes more prevalent, document imaging is becoming more important andwidespread. In a typical digital camera or scanner application, theimage data signals produced by the camera or scanner may be used by apersonal computer to reproduce an image of the object on a suitabledisplay device, such as a CRT or a printer.

A hand-held or portable digital camera is a digital camera which isdesigned to be hand held and pointed at the object or document beingimaged. A hand-held or portable optical scanner is an optical scannerwhich is designed to be moved by hand across the object or documentbeing scanned. The imaging device, either digital camera or scanner, maybe connected directly to a separate computer either by a data cable orwireless data link. If so, the data signals produced by the imagingdevice may be transferred to the separate computer “on the fly,” i.e.,as the image data are collected. Alternatively, the imaging device mayinclude an on-board data storage system for storing the image data. Theimage data may then be downloaded to a separate computer after thescanning operation is complete by any convenient means, such as via acable or an optical infrared data link.

Digital cameras are well-known in the art and various components thereofare described in U.S. patent application, Ser. No. 09/189,128, for TWOPIECE SYSTEM FOR DOCUMENT IMAGE CAPTURE of Thomas C. Oliver, U.S. patentapplication, Ser. No. 09/295,865, for DIGITAL CAMERA WITH INERTIALPOSITION SENSING of David D. Bohn U.S. Pat. No. 4,131,919, U.S. Pat. No.4,420,773, and U.S. Pat. No. 4,541,010, all of which are herebyincorporated by reference for all that they disclose.

A typical hand-held digital camera or optical scanner may includeillumination and optical systems to accomplish imaging of the object.The illumination system illuminates all or a portion of the object,whereas the optical system collects light reflected by the illuminatedtarget region and focuses the reflected light onto the surface of aphotosensitive detector positioned within the imaging device. By way ofexample, the illumination system may include a light source (e.g., afluorescent or incandescent lamp or an array of light emitting diodes(LEDs)). The optical system may include a lens and/or mirror assembly todirect and focus the image of the illuminated target region along theoptical axis of the optical system onto the surface of the detector.

The photosensitive detector used to detect the image light focusedthereon by the optical system may be a charge-coupled device (CCD),although other devices may be used. A typical CCD may comprise an arrayof individual cells or “pixels,” each of which collects or builds-up anelectrical charge in response to exposure to light. Since the quantityof the accumulated electrical charge in any given cell or pixel isrelated to the intensity and duration of the light exposure, a CCD maybe used to detect light and dark spots on an image focused thereon.

The term “image light” as used herein refers to the light that isfocused onto the surface of the detector array by the optical system.The image light may be converted into digital signals in essentiallythree steps. First, each pixel in the CCD detector converts the light itreceives into an electric charge. Second, the charges from the pixelsare converted into analog voltages by an analog amplifier. Finally, theanalog voltages are digitized by an analog-to-digital (A/D) converter.The digital data then may be processed and/or stored as desired.

Portable imaging devices of the type described above are not withouttheir problems. For example, when a portable imaging device ispositioned over a document, it is difficult, if not impossible, toperfectly orient the imaging device by hand so that the optical axis isperpendicular to the document. The task is easier with portable scannerswhich may comprise a flat base to hold against the document. However, asportable scanners become smaller, their bases become increasingly narrowand correct orientation becomes more difficult.

If the imaging device is not held with the optical axis perpendicular tothe document face, the resulting image of the document will be stretchedand may be blurry and illegible. When the imaging device is notperpendicular, (i.e., is held at an angle other than 90° to the documentface), one area of the document is closer to the imaging device'sphotosensitive detector than the other. Portions of the document whichare closer to the imaging device will appear larger, or zoomed in, inthe final image. Portions of the document which are farther from theimaging device will appear smaller, or zoomed out, in the final image.The image will also appear compressed along an axis between the closerarea and the more distant area. For example, a circle on the documentwould appear elliptical, or a square on the document would appearrectangular or trapezoidal in the resulting image. Finally, dependingupon the depth of field of the imaging device's optical system, portionsof the final image may be out of focus.

Digital cameras may be held in place over a document with a fixture suchas a tripod or bracket to help hold them in a given orientation.However, it is difficult to properly orient a digital camera even whenheld in such a fixture if the fixture allows for angular adjustment, asmost common tripods do. Some tripods include an air bubble tilt meter,but bubble meters are not very accurate and offer no feedback for largeangles when the bubble moves beyond the viewable window. Furthermore,the usefulness and portability of a digital camera requiring a tripod orfixture for document imaging is greatly limited.

A need therefore exists for a system to automatically maintain avertical orientation of the optical axis in an imaging device,perpendicular to a document positioned below the imaging device. A needfurther exists for a system allowing the imaging device to be used innon-vertical applications as well as document imaging.

SUMMARY

To assist in achieving the aforementioned needs, the inventor hasdevised an electronic imaging device having an optical assemblypivotally mounted therein. The pivot mount allows the optical assemblyto be pulled by gravity into a vertical orientation over a document.This improves image quality by aligning the optical axis of the opticalassembly perpendicularly with respect to the document, preventing imagedistortion.

An imaging device for document imaging having features of the presentinvention may comprise a housing and an optical system having a lenssystem and an optical detector. The optical system is responsive toimage light reflected by an object and produces image datarepresentative of the image light. The optical system is pivotallymounted to said housing and is biased toward a vertical orientationinside said housing by gravity.

The invention may also comprise an electronic imaging assemblycomprising a body portion, an imaging means for focusing, directing, andsensing image light, and a mounting means. The first means is pivotallymounting to the body portion by the mounting means so that the imagingmeans may be pulled by gravity around the mounting means to verticallyorient an optical axis of the imaging means.

The invention may also comprise a digital camera comprising a bodyportion, a gimbal mounted to the body portion, and an optical systemmounted in the gimbal so that the optical system is free to pivot underthe force of gravity in the body portion.

The invention may also comprise an imaging device for document imaging,comprising a body portion, an optical assembly, and a pivotal mountingbracket, whereby the optical assembly is pivotally mounted to the bodyportion. The imaging device also comprises a lock having a lockedposition and an unlocked position. The optical assembly may be lockedinto place relative to the body portion when the lock is in the lockedposition. The optical assembly may pivot about the pivotal mountingbracket when the lock is in the unlocked position.

BRIEF DESCRIPTION OF THE DRAWING

Illustrative and presently preferred embodiments of the invention areshown in the drawing, in which:

FIG. 1 is a front view of a digital camera as it may be used fordocument imaging, having a tilted orientation;

FIG. 2 is a front view of the digital camera of FIG. 1 wherein the imagelight optical axis has a vertical orientation;

FIG. 3 is a diagram of a digital camera as it may be used for documentimaging;

FIG. 4 is a diagram of the digital camera of FIG. 2 having a tiltedorientation;

FIG. 5 is a perspective cutaway view of a digital camera showing agimbal mounted optical system with a friction lock;

FIG. 6 is a perspective cutaway view of a digital camera showing a balland socket mounted optical system;

FIG. 7 is a cross-sectional view of the digital camera of FIG. 5;

FIG. 8 is a front view of a gimbal mounted optical system with a ringand finger lock assembly in the unlocked position;

FIG. 9 is a front view of the gimbal mounted optical system of FIG. 7with the ring and finger lock assembly in the locked position;

FIG. 10 is a bottom view of the ring and finger lock assembly of FIG. 7;

FIG. 11 is a front view of a gimbal mounted optical system with aplunger lock assembly in the unlocked position;

FIG. 12 is a front view of the gimbal mounted optical system of FIG. 10with the plunger lock assembly in the locked position;

FIG. 13 is a front view of a gimbal mounted optical system;

FIG. 14 is a front view of the gimbal mounted optical system of FIG. 12with a locking ring cap attached; and

FIG. 15 is a bottom view of the locking ring cap of FIG. 13.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An electronic imaging device 10 may be used to detect and store theimage of an object in electrical form. Typical types of electronicimaging devices include digital cameras and scanners. As digital camerasand scanners have become more portable and computers have become morewidely used, document imaging has developed into a very useful tool. Adocument 20 which may contain both text and graphics may beelectronically photographed or scanned, and the resulting imagetransferred to a computer, manipulated, combined with other documents orinformation, and printed or transferred across networks to computersacross the world. Text contained in an electronic image can also beconverted from graphical form to a text file by optical characterrecognition (OCR) software, allowing the text to be easily edited ormanipulated.

Flat bed image scanners may be used to easily scan an entire document inone pass, but are typically large, desk bound machines which are noteasily portable. Smaller portable hand-held scanners have become moreprevalent, allowing a near-pocket size device to scan a document inmultiple passes which are then stitched together to form a single imagefile representing the entire document.

Digital cameras are well-known in the art and are analogous to ordinaryfilm-type cameras, except that the film is replaced with an electronicphotosensor (e.g., a two-dimensional CCD array). The electronicphotosensor array converts the light received by the camera intoelectronic signals, which may be digitized and stored as digital imagedata. For example, the resulting digital image data may be stored in anelectronic memory system, such as random access memory (RAM), or may bestored on a magnetic or optical disk of the type commonly used to storedigital data.

Digital cameras offer considerable advantages over conventionalfilm-type cameras in that the digital image data may be stored,processed, and/or reproduced with ease. The relative ease of handlingand processing the digital image data produced by digital cameras allowsusers to readily enlarge, reduce, or otherwise modify the digital imagedata to create any of a wide; range of photographic effects and styles,as well as to easily capture the image of a document and convert text inthe image to a text file.

However, digital cameras and portable scanners do have disadvantages. Asthey become smaller, more portable, and easier to use, it becomesincreasingly more difficult to properly align them over the document. Ifthe imaging device is tilted with respect to the document, the resultingimage is distorted and OCR software is less effective at recognizing andconverting text in the image. Digital cameras held in the air over adocument are particularly difficult to align perpendicularly with adocument. Portable scanners are somewhat easier, to align, since theymay be placed against the document. However, the scan head of a portablescanner may be several inches long but only about an inch wide, allowingthe portable scanner to rock back or forth during the scanning motion.This causes the optical axis of the scanner to tilt with respect to thedocument which may distort the final image.

An exemplary imaging device 10 is illustrated in FIG. 1 as it may beused in document imaging. The imaging device may comprise any type ofelectronic imaging device which may be used for document imaging, suchas a portable scanner. The exemplary embodiment of an imaging device 10illustrated in FIG. 1 comprises a digital camera.

The imaging device 10 illustrated in FIG. 1 is held over an object, suchas a document 20, in the hand 22 of a user. The user has positioned theimaging device 10 but has oriented it at an angle with respect to thedocument 20. Image light (e.g., 32 and 34) is reflected from thedocument 20 into the optical system 44 of the imaging device 10.

The optical axis 24 of the imaging device 10 is aligned normally withthe housing or body portion 42 of the imaging device 10, i.e., thehousing 42 and the optical system 44 are tilted together at the sameangle 30. In contrast, the optical axis 124 of the imaging device 110illustrated in FIG. 2 has been vertically oriented to prevent distortionof the resulting document image.

The tilted optical axis 24 shown in FIG. 1 illustrates the normaloperation of a typical digital camera when it is improperly oriented, orthe operation of an imaging device 10 according to a presently preferredembodiment having a locking device in place to secure the optical system44 to the housing 42, as will be described in more detail hereinafter.

The image light 32 reflected to the optical system 44 from the area 50between the left side 46 of the target region and the optical axis 24will form the left half of the resulting document image (not shown). Theimage light 34 reflected to the optical system 44 from the area 52between the right side 54 of the target region and the optical axis 24will form the right half of the resulting document image. The imagingdevice 10 shown in FIG. 1 is tilted in the users hand 22, causing theoptical axis 24 to form a non-zero angle 30 with respect to the verticalaxis 26 which is perpendicular to the document 20. As a result of thisnon-zero angle 30, the left area 50 has a width 36 which is greater thanthe width 40 of the right area 52. In the resulting document image, theleft area 50 and the right area 52 will appear as the same size, eachforming half of the final image. The tilted imaging device 10 willcompress the larger left area 50 into the same space in the final imageas the smaller right area 52. Therefore, text or images nearer the leftside 46 of the document 20 will appear smaller, or compressed, whencompared with text or images nearer the right side 54.

A preferred embodiment of an imaging device 110 for document imaginghaving a gimbaled or otherwise pivoting optical system 144 is shown inFIG. 2. The camera body 142 is held in the users hand 122 over adocument 120. The optical system 144 is mounted to the camera body orhousing 142 on a gimbal or other pivoting mounting bracket (not shown),to be described in more detail hereinafter. The mounting bracket allowsthe optical system 144 to pivot under the force of gravity independentof the tilt angle of the housing 142, within a range of tilt angleswhich may be inadvertently caused during normal document imagingoperations. The mounting bracket may allow the optical system 144 topivot either along one or two axes within the camera housing 142according to various embodiments.

Although the camera housing 142 is tilted and is not held vertical orperpendicular with respect to the document 120, the optical system 144is pulled into a vertical orientation by gravity inside the camerahousing 142. When the document 120 is placed on a level, horizontalsurface below the imaging device 110, the optical axis 124 of thepivoted optical system 144 is perpendicular to the document 120. Theresulting document image will therefore be undistorted by the angle ofthe housing 142.

The left document area 150 between the left side 146 and the opticalaxis 124 is reflected in image light 132 on the left side, and the rightdocument area 152 between the right side 154 and the optical axis 124 isreflected in image light 134 on the right side. Since the optical axis124 is perpendicular to the document, the width 136 of the left area 150is equal to the width 140 of the right area 152, and the image of thedocument 120 will be captured properly, without compression ordistortion.

Before describing an imaging device 10 for document imaging having agimbaled or otherwise pivoting optical system in more detail, anexemplary digital camera and portable scanner which may employ apivoting optical system will be described. However, it is important tonote that the gimbaled or otherwise pivoting optical system may beemployed in any imaging device for document imaging, and should not beviewed as limited to the exemplary devices discussed herein.

With the foregoing considerations in mind, a digital camera 210 (FIG. 3)may comprise a main body portion 242 which is sized to receive thevarious systems and components required by the digital camera. Forexample, in the embodiment shown and described herein, the body 210 issized to receive the optical system 244, a pivoting optical systemmounting bracket 264, and electronic systems such as a controller andmemory 258 to process and store the image data. It is generallypreferred, but not required, that the controller and memory 258 of thedigital camera 210 include an image processing system to allow the imagedata collected by the camera to be processed independently, i.e.,without having to connect the camera to a separate computer or othersuch device to process and format the image data. The body 242 may alsobe sized to receive a power source 256 such as a battery. The digitalcamera 210 preferably includes an illumination system such as a flashmounted on the outside of the body 210. Each of the foregoing systemsand devices will now be described in detail.

The main body or housing 242 of the digital camera 210 may comprise agenerally rectangularly shaped structure sized to receive the variousinternal components of the camera 210. For example, in the embodimentshown and described herein, the main body 210 is sized to receive thevarious electronic components comprising the power source 256,controller and memory 258, pivoting mounting bracket 264, and opticalsystem 244. The body 210 may also be sized to receive other components,such as a battery system 256 and a portable media mass data storagesystem 258 (e.g., a magnetic floppy disk drive or an optical disk drive(not shown)) to allow image data produced by the digital camera 210 tobe stored on portable media (e.g., a magnetic or optical disk). However,since digital cameras and camera bodies are well-known in the art andcould be easily provided by persons having ordinary skill in the artafter having become familiar with the teachings of the presentinvention, the main body 242 utilized in one preferred embodiment of thepresent invention, as well as the various ancillary systems and devices(e.g., battery systems and media recording systems) that may be utilizedin one preferred embodiment of the present invention will not bedescribed in further detail herein.

The optical system 244 may comprise a lens assembly 262 and an imagesensor 260. The lens assembly 262 collects and focuses on the imagesensor 260 image light 232 and 234 reflected by the object or document220. The image sensor 260 in turn produces image data (not shown) thatare representative of the image light 232 and 234 reflected by thedocument 220. The image data (not shown) produced by the image sensor260 may be directed to the controller and memory 258.

The lens assembly 262 may comprise any of a wide range of lensassemblies that are well-known in the art and readily commerciallyavailable. For example, in one preferred embodiment, the lens assembly262 may comprise a lens assembly available from Pentax of Japan. Thelens assembly 262 may be mounted to the optical system 244 according toany of a wide variety of mounting systems and methods well-known in theart. The image sensor 260 may be mounted to a printed wiring board (notshown) that may be secured within the optical system 244 of camera 210.The image sensor 260 may comprise a two dimensional photosensor array ofthe type that is well-known in the art and readily commerciallyavailable. Consequently, the present invention should not be regarded aslimited to any particular type of image sensor 260. However, by way ofexample, in one preferred embodiment, the image sensor 260 may comprisea two dimensional CCD array.

Since optical systems of the type utilized in digital cameras arewell-known in the art and readily commercially available, and since adetailed description of the optical system is not required to understandor practice the present invention, the optical system 244 and relatedcomponents (e.g., lens assembly 262 and image sensor 260) that may beutilized in one preferred embodiment of the present invention will notbe described in further detail herein.

The optical system 244 may be mounted to the interior of the camera body242 using a pivoting mounting bracket 264. For example, the pivotingmounting bracket 264 may comprise a gimbal ring 266 mounted to thecamera body 242 on two opposite sides by outer mounting pins 268, whilethe optical system 244 is mounted inside the gimbal ring 266 on twoopposite sides by inner mounting pins 270. The outer mounting pins 268and inner mounting pins 270 form two axes at right angles to each other,allowing the gimbal ring 266 to pivot along one axis inside the camerabody 242, and the optical system 244 to pivot along another axis atright angles to the first inside the gimbal ring 266. As the cameratilts, the optical system 244 may remain in a vertical orientation,since the inner and outer mounting pins 270 and 268 allow the opticalsystem 244 to pivot in all directions.

A flash (not shown) may also be mounted to the exterior surface of thecamera body 242 to uniformly illuminate the document 220. The flash maycomprise any suitable illumination device, such as an incandescent bulb.

The gimbaled or otherwise pivoting optical system may also be employedin a portable scanner (not shown). A typical hand-held optical scannermay include illumination and optical systems to accomplish scanning ofthe object. The illumination system illuminates a portion of the object(commonly referred to as a “scan region”), whereas the optical systemcollects light reflected by the illuminated scan region and focuses asmall area of the illuminated scan region (commonly referred to as a“scan line”) onto the surface of a photosensitive detector positionedwithin the scanner. Image data representative of the entire object thenmay be obtained by placing the portable scanner against the object andsweeping the scan line across the entire object, usually by moving thehand-held scanner with respect to the object. By way of example, theillumination system may include a light source (e.g., a fluorescent orincandescent lamp or an array of light emitting diodes (LEDs)). Theoptical system may include a lens and/or mirror assembly to direct andfocus the image of the illuminated scan line onto the surface of thedetector.

The photosensitive detector used to detect the image light focusedthereon by the optical system may be a charge-coupled device (CCD),although other devices may be used.

Although a portable scanner does not capture the entire image of adocument simultaneously, the image can be distorted or compressed aswith a digital camera if the portable scanner is tilted or rocked backand forth during the scanning operation. By mounting the optical systemin a gimbaled or otherwise pivoting mounting bracket, the optical systemcan be maintained in an orientation perpendicular to the document evenwhen the portable scanner is improperly tilted.

Having generally described a gimbaled optical system as it may be usedin a digital camera or a portable scanner, the gimbaled or otherwisepivoting optical system will now be described in more detail.

Referring now primarily to FIGS. 3 and 4, a presently preferredembodiment of a digital camera 210 may comprise an optical system 244mounted on a gimbal 264. The gimbal 264 may comprise a gimbal ring 266mounted to the camera body 242 on two opposite sides by outer mountingpins 268, while the optical system 244 is mounted inside the gimbal ring266 on two opposite sides by inner mounting pins 270. The outer mountingpins 268 and inner mounting pins 270 form two axes at right angles toeach other, allowing the gimbal ring 266 to pivot along one axis insidethe camera body 242, and the optical system 244 to pivot along anotheraxis at right angles to the first inside the gimbal ring 266. As thecamera tilts, the optical system 244 may remain in a verticalorientation, since the inner and outer mounting pins 270 and 268 allowthe optical system 244 to pivot in all directions.

The optical system 244 is mounted to the gimbal ring 266 near an upperend 241 of the optical system 244 so that the center of gravity of theoptical system 244 lies below the gimbal mounting bracket 264. Thisallows the force of gravity to pull the optical system 244 into avertical orientation, keeping the optical axis 224 perpendicular to thedocument 220. As illustrated in FIG. 4, as the camera body or housing242 is tilted, the optical system 244 remains vertical, forming anon-zero angle 231 between the optical system 244 and the housing 242 ofthe camera 210.

The gimbal 264 may have either one or two pivotable axes. For thepreferred embodiment illustrated in FIGS. 3 and 4, the gimbal 264 hastwo pivotable axes along the inner and outer mounting pins 270 and 268,which are located at right angles to each other. If the camera 210 istilted to the right as shown in FIG. 4, the housing 242 and gimbal ring266 tilt, and the optical system 244 remains vertical by pivoting aboutthe inner mounting pins 270 inside the gimbal ring 266. If the camera210 were tilted into the page, the housing 242 would tilt, and thegimbal ring 266 and optical system 244 would remain vertical by pivotingtogether about the outer mounting pins 268. Normally, the camera 210will not be tilted along only one of the axes established by the innerand outer mounting pins 270 and 268, thus the gimbal ring 266 andoptical system 244 will pivot about both axes simultaneously to remainvertical.

The digital camera 210 may also comprise a flexible cable (not shown)connecting the image sensor 260 in the optical system 244 to thecontroller and memory 258 in the housing 242, so that a non-zero angle231 between the optical system 244 and the housing 242 will not breakthe connection. The digital camera 210 may also comprise any suitableconnection method for transferring image data between the optical system244 and systems in the housing 242, such as wireless transmission orrotating electrical connections in the mounting pins 268 and 270.

The gimbaled or otherwise pivotable mounting bracket (e.g., 264) may bedamped to prevent oscillations during use. For example, the mountingpins 268 and 270 may be tightly mounted so that friction is high enoughto allow the desired pivoting action while preventing oscillation.Alternatively, a viscous fluid may be placed between moving parts in thebracket to slow the pivoting action. Any suitable damping means nowknown or that may be developed in the future may be applied to thebracket as needed, according to the design requirements of the imagingdevice.

Another embodiment of a gimbal mounted optical system is illustrated inFIG. 5. A digital camera 310 may comprise a housing 342, in which anoptical system 344 is mounted on a gimbal 364. A gimbal ring 366 ismounted to the inside of the housing 342 on outer mounting pins 368which allow the gimbal ring 366 to pivot back and forth around an Xaxis. The optical system 344 is mounted inside the gimbal ring 366 oninner mounting pins 370 which allow the optical system 344 to pivot backand forth around a Y axis.

The gimbal mounted optical system may also comprise a lock having anunlocked position (shown in FIG. 5) and a locked position. The lockcomprises a locking rod 374 which may be pressed and held against asemi-spherical dome 372 to frictionally hold the optical system 344 inposition. When the rod 374 is pressed against the dome 372, the lock isin the locked position and the optical system 344 is prevented frompivoting. When the rod 374 is retracted from the dome 372, the lock isin the unlocked position and the optical system may freely pivot aboutthe inner and outer mounting pins 370 and 368 under the pull of gravity.The optical system 344 is mounted in the gimbal 364 at an upper end 341of the optical system, so that the center of gravity of the opticalsystem lies below the gimbal 364. The dome 372 is attached to theoptical system 344 just above the gimbal 364. As a result, as theoptical system 344 pivots on the gimbal 364, the surface of the dome 372slides about like a rotating ball, but does not shift position. Thelocking rod 374 may therefore contact the dome 372 at the same location,regardless of how the optical system 344 is tilted.

The lock allows the digital camera 310 to be used in non-verticalapplications, such as photographing scenery. The lock may be moved intothe unlocked position when using the camera 310 for document imaging,allowing the optical system 344 to pivot into a vertical orientation.The lock may then be moved into the locked position, preventing theoptical system 344 from pivoting so that the camera 310 may be raisedinto a horizontal or other orientation.

The optical system 344 and dome 372 may be formed as a single integralunit, with the image sensor (not shown) located in either the opticalsystem 344 or the dome 372. Alternatively, the optical system 344 anddome 372 may comprise independent elements and may be fastened togetherwith any suitable means, such as an adhesive layer. The various elementsof the digital camera 310 may be fabricated of any suitable material,such as plastic or metal. The moving parts of the gimbal 364 may be madeof low friction materials to facilitate pivoting, or may be made ofhigher friction materials to dampen the pivoting action.

In another embodiment illustrated in FIGS. 6 and 7, a digital camera 410may comprise an optical system 444 mounted in a housing 442. The opticalsystem 444 is pivotally attached to the housing 442 with a ball andsocket bracket 476. An extension arm 480 is connected at one end to thehousing 442, while the other end is connected to a socket 479. Thesocket 479 comprises a spherical interior sized to fit a ball 478,allowing the ball 478 to fit within the interior and rotate withoutshifting. The bottom portion of the socket 479 is left open to allow asupport arm 481 connected to the ball 478 to extend down from the ball478.

The size of the open bottom of the socket 479 may be varied by thoseskilled in the art according to several design considerations. Thespherical interior of the socket 479 should remain just larger than asemi-sphere in order to hold the ball 478 in the socket, preventing theball 478 from dropping out the bottom of the socket 479. A large openingin the socket will allow the support arm 481 to swivel around largerangles, correcting for larger camera orientation angles. The size of theopening is preferably optimized to allow the ball 478 to be snapped intothe socket 479 under pressure, but to prevent the ball 478 from fallingout of the socket 479 under normal operating conditions.

The fit between the ball 478 and socket 479 may also be varied to varythe ease with which the optical system 444 may pivot. To dampen and slowthe pivoting action, the fit between the ball 478 and socket 479 may bemade relatively tight. To allow the optical system 444 to pivot morefreely, the fit between the ball 478 and socket 479 may be made loose.Several considerations should be taken into account during design, suchas weight of the optical system 444, materials used in the ball 478 andsocket 479, the operating environment of the camera 410, etc.

The housing 442 is sized to accept the optical system 444 and ball andsocket bracket and to allow the optical system 444 to pivot or swinginside the housing 442. The range of motion allowed the optical system444 may vary according to the needs of the camera designer andmanufacturer. For example, to correct only small errors in orientation,the housing 442 may be formed with little extra space for the opticalsystem 444 to swing. Alternatively, to allow the optical system 444 toswing more freely to correct greater errors in orientation, a greateramount of extra space should be included between the optical system 444and the housing 442.

The digital camera 410 may also comprise a locking arm 474 which maypass through a hole 482 in the socket 479. The locking arm 474 may thenbe pressed against the ball 478, frictionally restricting its rotationin the socket 479 and locking the optical system 444 in place. Thelocking arm 474 may best be seen in FIG. 7 as it passes through the hole482 in the socket 479. The locking arm 474 may comprise a simple rodpassing from the exterior of the housing 442 through the hole 482 in thesocket 479, allowing a user to press and hold the end of the locking arm474. Alternatively, a locking assembly (not shown) may be used to movethe locking arm 474 between the locked and unlocked positions and tohold the locking arm 474 in place.

The digital camera 410 may also comprise an image sensor 460, lensassembly (not shown), and other components mounted in the optical system444 and in the housing 442 as needed.

Referring now to FIGS. 8, 9, and 10, a digital camera may comprise alock base 584 fixedly mounted inside the housing of the digital camera.An optical system 544 may be pivotally mounted below the lock base 584with a gimbal bracket 585, allowing the optical system 544 to pivot andswing inside the housing.

The gimbal bracket 585 may comprise a first gimbal arm 586 having awidth substantially equal to the width of the lock base 584. The firstgimbal arm 586 may be pivotally mounted to the lower end of the lockbase 584 on first gimbal supports 588. A second gimbal arm 587 may bepivotally mounted at right angles to the first gimbal arm 586, and theoptical system 544 may be mounted is below the second gimbal arm 587 onsecond gimbal supports 589. As the camera is tilted, the housing (notshown), and the fixedly attached lock base 584 tilt along with it. Theoptical system 544 pivots on the gimbal bracket 585 to remain in avertical orientation. The first gimbal arm 586 allows the optical system544 to pivot along one axis, while the second gimbal arm 587 allows theoptical system to pivot along another axis at right angles to the first,providing full motion around the long axis of the camera.

The gimbal elements may correspond to any known gimbal types or to anydeveloped in the future. They may be designed with a stiff action todampen oscillations in the optical system 544 relative to the housing,or may be left looser to facilitate pivoting. A separate dampeningmechanism, such as a viscous fluid between moving parts, may also beincluded as desired.

The digital camera may also include a lock, comprising a slide ring 590sized to fit over the lock base 584 and to slide up and down it. Theslide ring 590 has at least one locking fingers 591 extending down fromit, spaced to fit snugly around the sides of the optical system 544 whenthe lock is in the locked position. In a preferred embodiment, fourlocking fingers 591 extend down from the slide ring 590, as seen fromthe bottom in FIG. 10.

The at least one locking fingers 591 may alternatively engage in atleast one hole (not shown) in the top of the optical system 544 toprevent the optical system 544 from pivoting.

When in the unlocked position (see FIG. 8), the slide ring 590 ispositioned near an upper end of the lock base 584, and the attachedlocking fingers 591 lie alongside the lock base 584. When in the lockedposition, the slide ring is slid down the lock base 584 to rest near alower end of the lock base 584, causing the locking fingers 591 toextend down between the gimbal arms 586 and 587 to fit around the sidesof the optical system 544, as illustrated in FIG. 9. The optical system544 is thereby held in position relative to the lock base 584 and to thehousing, preventing it from pivoting under the force of gravity.

To move the slide ring 590 up and down the lock base 584, a slide lever(not shown) may connect to the slide ring 590 and extend to the exteriorof the camera housing, allowing a user to manipulate the slide ring 590.The slide ring 590 is preferably sized to fit snugly over the lock base584, preventing it from inadvertently shifting.

Referring now to FIGS. 11 and 12, another embodiment of a digital cameramay comprise an optical system 644 mounted to a housing 642 by a gimbalbracket 685. The gimbal bracket 685 may comprise a first gimbal arm 686,pivotally attached at two ends to the housing 642. A second gimbal arm687 may be pivotally attached at right angles to the first gimbal arm686 near a midpoint. The optical system 644 may be suspended below thesecond gimbal arm 687 by a pair of gimbal supports 689. The opticalsystem 644 may thereby pivot freely about the gimbal bracket 685 insidethe housing 642.

The digital camera may also comprise a lock mechanism, comprising atleast one locking arms 691 spaced to fit around and engage with thesides of the optical system 644. The locking arms 691 may be supportedby a lock ring or disk 690 located above the optical system 644. Thelock ring is actuated by a plunger 692 which may be depressed to slidethe locking arms 691 between the gimbal arms 686 and 687 and around thesides of the optical system 644. To support and position the plunger692, a guide hole 693 may be located in a horizontal wall member 694above the optical system 644, allowing the plunger 692 to move up anddown between the locked and unlocked positions without shifting fromside to side.

In another embodiment illustrated in FIGS. 13, 14, and 15, a digitalcamera may comprise an optical system 744 pivotally mounted to a housing742 on a gimbal bracket 785. The gimbal bracket 785 may comprise a firstgimbal arm 786, pivotally mounted at two ends to the housing 742 oranother support member fixedly located within the housing 742. A secondgimbal arm 787 may be pivotally attached at right angles to the firstgimbal arm 786, allowing the gimbal bracket 785 two degrees of motionwithin the housing 742. The optical system 744 may be suspended belowthe gimbal bracket 785 by a pair of gimbal supports 789 pivotallyattached near the ends of the second gimbal arm 787. As discussedpreviously, the housing 742 is large enough to leave empty space betweenthe housing 742 and the optical system 744, allowing the optical system744 to freely pivot inside the housing 742.

In an alternative embodiment, the optical system 744 may be pivotallymounted inside the housing 742 with one or more hinges (not shown),allowing the optical system 744 to pivot in one or more directions,depending upon the number of hinges used.

The digital camera may also comprise a locking ring cap 795. The lockingring cap comprises a ring with a side wall 797 defining a center hole796 through which image light may pass. The locking ring cap 795 may beplaced around the lower end of the optical system 744 so that it fillsthe empty space between the optical system 744 and the housing 742 in atleast three spaced apart locations, in order to prevent the opticalsystem 744 from swinging in any direction within the housing 742. Whenthe locking ring cap 795 is placed upon the camera, optical light maypass through the center hole 796 in the cap 795 to reach the opticalsystem 744.

The locking ring cap 795 is preferably sized to fit snugly between theoptical system 744 and the housing 742 so that it prevents pivoting andso that it will not fall off of the optical system 744 if jarred orbumped. Alternatively, corresponding ridges and valleys in the ring cap795 and the optical system 744 or housing 742 may engage when the cap795 is in the locking position, preventing the cap 795 frominadvertently falling from the camera. The side wall 797 of the lockingring cap 795 may also be beveled near the top to facilitate insertionaround the optical system 744.

The locking rings and cap disclosed herein have the advantage ofcentering the optical system within the housing, simplifying imagecomposition, and providing positive engagement to securely lock theoptical system in place. The frictional locking arms, in contrast, maylock the optical system at any desired angle, but do not providepositive engagement, thus provide a less secure lock.

While presently preferred illustrative and exemplary methods ofpivotally mounting the optical system (e.g., 44) in a camera housing(e.g., 42) have been disclosed, the optical system 44 may be mounted inthe housing 42 with any suitable pivoting bracket now known, or whichmay be developed in the future, without departing from the inventiveconcepts disclosed herein. Therefore, the gimbal optical system fordocument image capture should not be regarded as limited to the bracketsdescribed in detail. It is to be understood that the inventive conceptsmay be otherwise variously embodied and employed, and that the appendedclaims are intended to be construed to include such variations, exceptas limited by the prior art.

1. An imaging device for document imaging, comprising: a body portion;an optical assembly; a pivotal mounting bracket; whereby said opticalassembly is pivotally mounted to said body portion; a lock having alocked position and an unlocked position, whereby said optical assemblymay be locked into place relative to said body portion when said lock isin said locked position, and where said optical assembly may pivot aboutsaid pivotal mounting bracket when said lock is in said unlockedposition, and wherein said lock comprises at least one locking fingersoperatively associated with said body portion, said at least one lockingfingers engaging with said optical assembly when said lock is in saidlocked position to hold said optical assembly in place relative to saidbody portion.
 2. An imaging device for document imaging, comprising: abody portion; an optical assembly; a pivotal mounting bracket, wherebysaid optical assembly is pivotally mounted to said body portion; a lockhaving a locked position and an unlocked position, whereby said opticalassembly may be locked into place relative to said body portion whensaid lock is in said locked position, and where said optical assemblymay pivot about said pivotal mounting bracket when said lock is in saidunlocked position, wherein said pivotal mounting bracket comprises agimbal; and wherein said lock comprises a ring cap comprising a ringwhich may be slid around said optical assembly to rest between saidoptical assembly and said body portion, preventing said optical assemblyfrom moving relative to said body portion.